Stilbene disulfonic acid derivatives



Patented Oct. 1950 STILBENE DISULFONIC ACID DERIVATIVES Ernst Keller and Reinhard Zweidler, Basel, Switzerland, assignors to J. R. Geigy A. G., Basel, Switzerland, a Swiss company No Drawing. Application July 11, 1949, Serial No. 104,136. In Switzerland July 23, 1948 6 Claims. (Cl. 260-507) The present invention is concerned with the manufacture of optical brightening agents. By this term is understood colorless, nearly colorless to faintly yellowish compounds which absorb light in the invisible part of the spectrum and emit a bluish-violet to bluish-green fluorescence in the visible range. Because of this fluorescence the optical brightening agents give a white appearance to their more or less colorless carriers. Optical brightening agents which fluoresce a greenish-blue are particularly valuable since they impart an especially pleasing white appearance, whereas those which fluoresce in the violet-blue part of the spectrum give a less suitable reddish appearance which may be displeasing at higher concentrations. The optical brightening agents according to the invention are distinguished by a very intense fluorescence and a particularly pleasant white appearance in the carriers treated.

Stilbene derivatives, particularly derivatives of 4.4'-diamino-stilbene have frequently been suggested as optical brightening agents and have ac;

2 producing purer shades in the case of light colored textile dyeings.

The new optical brightening agents are obtained by methods known per se, comprising the acylation with suitable derivatives of organic carboxylic acids, of. 4-amino-4'-styryl-stilbene-2.2'-

where Y stands for a colorless carbacyl radical and A stands for a colorless aromatic radical of the benzene series which may also contain substituents usual in simple benzene derivatives, or

their alkali salts, are distinguished by a very intense fluorescence in the green-blue part of the spectrum. They are thus excellently suited for brightening more or lesscolorless carriers or for o "carbacyl radicals.

disulfonic acids which may also be termed 1- (4'- amino-styryl) -4 styryl benzene-2.2-disulfonic acids and wherein the benzene ring-oi the 4- or 4'styryl group may also contain substituents usual in simple benzene derivatives, e. g., halogen, alkyl, alkoxy and sulfonic acid groups, etc. The amino compounds used in the invention are obtained by reduction of the nitro group to the primary amino group in the 4-nitro-4'-styry1-stil bene-2.2-disulfonlc acids, which can be readily prepared as described in copending application Ser. No. 104,135, filed July 11, 1949.

As acylating derivatives of organic carboxylic acids, acid anhydrides and acid halides may be used; for the introduction of aminocarboxylic acid radicals organic lsocyanates may also be used. The acylating agents may conveniently be reacted with the aqueous solution of an alkali salt of the amino compound used according to the invention at lower, ordinary or slightly raised temperatures, if desired, in a heterogeneous phase system for adding inert, water-insolubl solventsfor the acylating agent, such as benzene, toluene,

chlorobenzene, nitrobenzene and so on, or with the addition of water-miscible organic solvents for the acylating agent, which also act as solventpromoters, e. g., acetone. or again, ii required, in the presence of agents weakening or neutralising" mineral acids, such as sodium acetate, sodium, magnesium or calcium carbonate, magnesium oxide.

In the following description we term the organic carboxylic acid radicals introduced in this way We use this expression to make it clear that acyl radicals of other organic acids such as, e. g., those of organic sulionic, phosphoric or arsinic acids are excluded. It is well known that in the acyl derivatives or 4.4'-diaminostilbene-2.2'-disuiionic acid the nature 01 the acyl radical has a great influence on the intensity of fluorescense and the shade of the fluorescent light and is, in fact, often decisive in determining practical utility. However, in the case of the carbacyl derivatives of the present invention, this holds to only a very limited extent. For example, 4.4-di-acetylaminostilbene-2.2'-disulfonic acid is technically valueless because of too low an intensity of fluorencense and a much too reddish shade, whereas the acetyl compounds of 4-amino-4'- Ityryl-stilbene-2.2'-disulfonic acid according to the present invention have a pure bluish fluoresccnse of great intensity and are of great technical value. Thus, in principle, the acyl radicals of all colorless organic carboxylic acids may be used as substituents. in the optical brightening agents of the present invention. The radicals of lower alkyl-carboxylic acids, of lower phenyl-alkyl and phenoxv-alkyl carboxylic acids, of phenyl-carboxylic acids, of lower alkoxy-carboxylic acids and of phenylamino-carboxyllc acids are all of practical importance. The aromatic rings which may be present in the carbacyl group may contain substituents usual in simple benzene derivatives, such as halogen, alkyl. alkoxy, acylamino and sulfonic acid groups. etc. Depending in part on the nature of the carbacyl radical Y, the new optical brightening agents exhibit aflinity either for natural or regenerated cellulose fibres or for fibres consisting of keratin or numerous synthetic organic materials including, e. g., casein, superpolyamide and superpolyurethane fibres, as well as for silk and especially for W001. The compounds according to this invention which are most suitable for brightening cellulose fibres are those acylated by the radical of a phenylcarboxylic acid or a phenyiamino-carboxylic acid. The degree of affinity for cellulose fibres is such that these compounds can be used in very dilute solution, e. g., in washing and rinsing liquors for textiles. Benzoyl derivatives, in accordance with the present invention, are especially suitable as additives to washing and cleaning agents for the treatment of textiles because, in addition to giving very pure white shades, they do not accumulate on the fibre on repeated treatment of the same textiles, e. g., in domestic laundering. Such undesirable accumulation could finally lead to a dull appearance or even to an unpleasant, e. g., reddish shade, because of the slight self-color of the compounds. Compounds according to the invention which are acylated by the radical of a lower alkyl, alkoxy or phenoxy-alkyl carboxylic acid are suitable for brightening wool, thanks to the gOOd solubility in water of their alkali salts which makes it possible to use them in an acid dyebath. The acetyl and phenoxyacetyl derivatives are particularly useful in this connection.

An obvious pre-requisite for an optical brightening agent which is required to fiuoresce blue,

is the absence of any pronounced self-color. For

this reason no strong chromophores such as, e. g., azo groups, should be present in the compounds of the invention. Possible carriers of such strong chromophores would be the carbacyl radical Y and the radical of the benzene series A. Therefore, to make this requirement clear, we characterize these radicals A and Y as "colorless i. e. free from chromophores.

The brightening agents according to the present invention surpass optical brightening agents so far known in their intensity of fluorescence. The appropriately acylated derivatives give a previously unattained pure white appearance to chemically prebleached wool and, furthermore,

have according to constitution, better fastness towards water. washing and alkalis than known bleaching agents for wool. This is particularly true in comparison with 4.5-diphenyl-imidazole- Z-one-disulfonic acid, which is the most important technical optical bleaching agent for wool, although completely different chemically from the compounds of the present invention. The fact that the new optical brightening agents possess an outstandingly intense green-blue fluoresence is surprising, since it might have been supposed that the introduction of a further chromophoric styryl group into the already known stilbene derivatives would displace lightabsorption into the visible spectrum, this giving rise to strongly colored compounds.

The carbacyl derivatives of the invention can, according to composition, also be employed as additives to soap. Furthermore, they can also be used admixed with cheaper optical brightening agents which fiuoresce blue-violet, such as, e. g., 4.4'-di-(phenylureido)-stilbene 2.2 disulfonic acid. They are particularly suitable for this because their intense greenish-blue fluorescence tends to improve white shades.

-The optical brighteningagents according to the invention are, in the form of their alkali salts, more or less yellowish to light yellow powders which give practically colorless solutions in water and can be used in the usual way in washing and rinsing liquors or in dye-baths.

The following examples illustrate the invention without restricting it. Parts are by weight and temperatures in degrees centigrade. The relationship of parts by weight to parts by volume is that of kilograms to litres.

Example 1 30 parts of iron filings are mixed with 500 parts of water and 2 parts of concentrated hydrochloric acid. Next, 48.7 parts of 4-nitro-4'- styryl-stilbene-2.2-disulfonic acid are added, while stirring well, over the course of an hour, at -98. The mixture is maintained at this temperature for a further 3 hours and then made alkaline to phenolphthalein by the addition of about 2.0 parts of soda ash. After filtering hot, the solution is made neutral to litmus with a little concentrated hydrochloric acid, salted out with 20% common salt and the precipitate filtered off and dried. If the crude nitro compound is used, it will usually be found advantageous to add a little hydrosulfite to the hot reducing mixture in order to destroy colored impurities.

After drying, the 4-amino-4'-styryl-stilbene- 2.2-disulfonic acid is a yellowish powder, which gives a faintly yellowish solution in water. The compound dissolves in concentrated sulfuric acid giving a greenish-yellow solution. Dilute aqueous solutions fluoresce greenish in daylight, while in ultraviolet light a very strong green fluorescence is displayed.

The 4-nitro 4'- styryl-stilbene-2.2'-disulfonic acid can, of course, be reduced by other methods suitable for reducing the nitro to the amino group. Thus, instead of iron filings there may be used, for example, alkali sulfides, or hydrosulfites as reducing agents.

Example 2 45.7 parts of 4-amino-4'-styryl-stilbene-2.2'- disulfonic acid, prepared according to Example 1, are dissolved in water, with neutral reaction, 17 parts of crystalline sodium acetate are added and the mixture allowed to react at'30-32 with 21 partsotphenoxy-aoctylchlorideinmpartsoi benzene while stirring rapidly. Mter acylation is complete the reaction product is'salted out. isolatedanddried. When mthecompoundisa substance are suiiicient to bring about a bright, ening eflect. The dyeing on wool has excellent i'astness properties towards washing. water, acid and alkalis as well as good i'astness to light. 11101 I trampled 45.7 parts oi 4-amino-4'-styryl-stilbene-2.2'-

disuli'onic acid prepared as in Example 1 are dis- 55 solved in water, with neutral reaction. parts oi acetic anhydride are then added at -32% while stirring well. After the primary amino groups have disappeared the s-acetamino-istyryl-stilbtene-ZT-disulionic acid is salted out.

filtered oiiand dried. When dry the compound is a pure greenish-yellow colored powder whose dilute aqueous solution has a strong bluish-green fluorescence. Wool dyed from a weakly acid bath, especially when chemically prebleached. is $5 given a pure bluish-white appearance. The dye,- ing on wool has excellent iastness properties towards water. washing, acids and alkalis as well as having good fastness to light. The fact that a bluish white appearance. lines which have been optically bleached in this way have excellent iastness properties towards water. washing. acid andalkaliaswellasgoodiastneptolight. Cotton and other cellulose fibres in a bath containing Glaubers salt are also liven a very intense and pure white appearance with sood iastness properties.

lizapartsoioctylchloroiorinateareusedior the acylation instead of ethyl chloroiormate then the eJgoduct obtained shows similar brightening ei! trample 6 An aqueous solution of 46.! parts of the disodium salt of 4-amino-4-styryl-stilbene-2.2'-disulionic acid which can be prepared as described .in Example 1, is reacted with a benzene solution of 17 parts 0! phenylacetyi chloride, the acyl derivative isolated and dried. The greenish-yellow substance thus obtained is an excellent brightening agent for wool, nylon, silk, cotton and regenerated cellulose. The brightened fibres are a faintly bluish white shade with excellent tastness properties.

A product having similar good properties is obtained when 45.7 parts of 4-ainino-4'-styryl-stilbene-22'-disuli.'onic acid are reacted by the method described abovewith 14 parts of ethoxy- .acetyl chloride. All these products have the further outstanding feature that very small quantities of them suiilce to give an intense brightening eiiect.

Example 7 50.1 parts of 4-nitro-4'-(4"-methyl-'-styryl)- .stilbene-2.2'-disulionic acid are reduced to 4- .amino-4'-(4"-methy1 styryl) stilbene-2.2'-divery small amounts or the new compound are .sulionlc acid by the method described in Exsufilcient to produce the effect of a very pure white is especially noteworthy. The new substance is also eminently suitable for brightening silk, schappe and nylon. The brightening eiiect pearance.

Example 4 45.7 parts of 4-amino-4'-styryl-stilbene-2.2'- 6 disulionic acid are reacted with a benzene solution of 1'7 parts of benzoyl chloride in the presence of 17 parts oi. crystalline sodium acetate. After no more primary amino groups can be deample 1.

47.1 parts of this 4 amino-4'44" methyl- 'styryl) -stilbene-2.2'-disulionic acid are acetylated in aqueous solution with 16 parts of acetic 1 produced by this compound pal-emu on wool anhydrlde, the reaction product is isolated and and silk, has an outstanding pure white apdried. The product has a greenish-yellow appearance. It is a. valuable brightening agent and shows a pure, faintly bluish white shade with good Iastness properties on fibres such as wool, nylon, cotton and regenerated cellulose.

A similar product is obtained it the acylation is carried out with, e. g., 24- parts 0! phenoxyacetyl chloride. instead of with acetic anhydride, with 1 the addition of 17 parts of crystalline sodium t t 1 1 t m g; acetate as bufler. This product also has all the '2.2'-disulionlc acid is salted out of the waterbenzene system, filtered of! and dried. When dry -is.is greenish-yellow in appearance. It gives a pure white appearance to cellulose fibres dyed from a neutral bath and to wool or silk dyed from soff a weakly acid bath. The compound is specially I .1

suited for addition to washing agents and soap powders and to rinsing liquors for textiles. Only a very small amount need be addedto produce the desired eflect.

v EramPZeS 45.7 parts of 4-amino-4'-styryi-stilbene-2.2'- disulfonic acid, obtained as-in Example 1 are reproperties of a valuable brightening agent. It may be used for bleaching the most varied kinds oi! animal and vegetable fibres.

Example 8 2.2'-disulionic acid is reacted in the presence of a mineral acid binding agent and while stirring I well with a benzene solution of benzoyl chloride acted, conveniently in benzene-water solution, n the l n-produ t sal d o parated with 113 parts of ethyl chloroformate in the presence of 17v parts of crystalline'sodium acetate. In the dry state the end product is a greenishyellow powder which draws from a weakly acid and dried. This compound has a greenish-yellow appear- F ance and is a valuable brightening agent:.wliich gives a fine white, faintly bluish appearance with bath on the pro-bleached wool to which it gives 78" very good iastness properties to fibres oi the most veried types such as wool, silk. cotton end manner similar to that described in the examples regenented cellulose when the latter are treated are listed in the following table.

under suitable conditions with an aqueous soiution of the agent. Y-NH OH=OE OH=OH-A A series of further compounds with outstsndinl 5 brightening action, which can be prepared in s.

No? Y o om-O-o-om-oo w olQ-o-cm-oou om-o-Oo-cm-oo- 15.. CHr-OHe-C O- 22. CHr-CO- 2a... C -o-cH|-0o- QQQgOOOO-OOOO,

CHI

0-CHs O-GH:

wow

:u.......-.. O-o-om-oo- ONE-.0 0-

... CHI-0 0- 32.. CHa-C O- end nromntlo ou'boxyllo ncld ooyl radicals free iii-C O CH| K-O 0-CB:

31. cm-c o- --Nn-co-cm NK-OO-ClRl ea cm c o- I. CHI-CO What we claim is: 8. The compound of the formula Om-onw o-rm-Qon-oa@cn=ca-O Dan H 0:

An optical brightening agent! 4. The compound or the formula 1. A compound or the general formula Y-NH- cn==cn OH-OB-A 5o O Q P O 013 H 0| 0:3 H 0| I wherein Y represents an noyl radial looted 5. The compound 0! the formula.

Oom-oo-NnQon-onQcn=cn- 0-3 out Item the noun eonsla tin: of m muo. We. a. m compound of the formula o'm-o-oo- NnQ-on-on-Qcn-cnO om I on: 7 MT mm.

mm zwnmm.

Homeroom M- from chromophores, and A repreoenta an arena-- flondlcnlotthebenzenelerteetreelromchmmo- 2. Theeompound'o! the lonnule omoo-nn-q-on-onPon-on-O 

1. A COMPOUND OF THE GENERAL FORMULA 